fix(tracing): [v7] use web-vitals ttfb calculation

[AbhiPrasad]

Backport of #11185

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	80.45 KB (+0.44% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	71.46 KB (+0.36% 🔺)
@sentry/browser (incl. Tracing, Replay with Canvas) - Webpack (gzipped)	75.47 KB (+0.36% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	65.1 KB (+0.4% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	35.4 KB (+0.69% 🔺)
@sentry/browser (incl. browserTracingIntegration) - Webpack (gzipped)	35.29 KB (+0.68% 🔺)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	31.49 KB (+0.18% 🔺)
@sentry/browser (incl. sendFeedback) - Webpack (gzipped)	31.5 KB (+0.19% 🔺)
@sentry/browser - Webpack (gzipped)	22.74 KB (+0.25% 🔺)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	78.55 KB (+0.28% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	69.97 KB (+0.33% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	35.77 KB (+0.69% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	25.17 KB (+0.25% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	220.29 KB (+0.34% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	108.1 KB (+0.69% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	75.48 KB (+0.14% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	38.99 KB (+0.54% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	71.96 KB (+0.38% 🔺)
@sentry/react - Webpack (gzipped)	22.77 KB (+0.25% 🔺)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	89.8 KB (+0.32% 🔺)
@sentry/nextjs Client - Webpack (gzipped)	53.95 KB (+0.53% 🔺)
@sentry-internal/feedback - Webpack (gzipped)	17.28 KB (0%)